Can't get old computer to boot by itself

I have an old ASUS P53 laptop that I am trying to get Mountain Lion installed on. I tried following a little guide here (http://www.tonymacx86.com/threads/asus-p53e-laptop-sandy-bridge-lion-10-7-hackintosh.45043/) for this laptop. My issue was I could not for the life of me find out what he meant by "Chimera 1.8.0 bootloader, but need boot from flash and unmount Lion's partition to apply boot1h: dd if=boot1h of=/dev/rdisk0s2"
Particularly unmount lion and on. I decided to...

Can't get old computer to boot by itself